E-Wallet Application
Overview The E-Wallet Application is a microservices-based system designed to provide digital wallet functionality. It allows users to manage their accounts, perform transactions, and receive notifications. The application is built using Spring Boot and follows a microservices architecture for scalability and maintainability.
System Architecture
The application consists of four main microservices:
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User Service: Manages user accounts and authentication.
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Wallet Service: Handles user wallets and balances.
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Transaction Service: Manages money transfers between wallets.
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Notification Service: Sends notifications to users based on system events.
These services communicate with each other via RESTful APIs and use Apache Kafka for event-driven communication.
Technology Stack Java: 17 Spring Boot Spring Security Spring Data JPA PostgreSQL Redis Apache Kafka Maven
Microservices Overview
- User Service
Responsible for user management and authentication.
Key Components:
UserController: Handles user-related HTTP requests UserService: Implements business logic for user operations User: Entity representing user data UserRepository: Interface for database operations SecurityConfig: Configures security settings RedisConfig: Configures Redis for caching Database:
PostgreSQL for persistent storage Redis for caching
- Wallet Service
Manages user wallets and balances.
Key Components:
WalletController: Handles wallet-related HTTP requests WalletService: Implements business logic for wallet operations Wallet: Entity representing wallet data WalletRepository: Interface for database operations Database:
PostgreSQL
- Transaction Service
Handles money transfers between wallets.
Key Components:
TransactionController: Handles transaction-related HTTP requests TransactionService: Implements business logic for transactions Transaction: Entity representing transaction data TransactionDao: Interface for database operations KafkaConfig: Configures Kafka for event publishing
Database:
PostgreSQL Event Streaming: Kafka
- Notification Service Sends notifications to users based on system events.
Key Components:
NotificationService: Listens to Kafka topics and sends notifications EmailConfig: Configures email sending capabilities KafkaConfig: Configures Kafka for consuming events Event Streaming: Kafka
Data Flow:
API Documentation
User Service APIs:
POST /user/create: Create a new user
GET /user/profile-info: Get user profile information
GET /user/username/{username}: Get user details by username
Wallet Service APIs:
POST /wallet/update: Update wallet balance
Transaction Service APIs:
POST /transaction/initiate: Initiate a new transaction
Security Spring Security is implemented for authentication and authorization. Passwords are encrypted using BCrypt. JWT tokens are used for maintaining user sessions.
Caching Redis is used in the User Service for caching frequently accessed user data.
Event Streaming Kafka is used for asynchronous communication between services. Key topics include: user_created, transaction_completed.
Monitoring and Logging Spring Actuator for health checks and metrics. ELK Stack (Elasticsearch, Logstash, Kibana) for centralized logging.
Future Enhancements Implement circuit breakers for improved fault tolerance. Add more sophisticated fraud detection in the Transaction Service. Expand notification channels (e.g., SMS, push notifications).